tRNA (m5U54)-methyltransferase (RUMT) catalyzes the S-adenosylmethionine-dependent methylation of uridine-54 in the T-loop of transfer RNA. It has been suggested that a substantial conformational change in the tRNA molecule is necessary for methylation to occur, as the C5 of U54 is inaccessible to solvent. From the three-dimensional structure of tRNA, U54 is stacked between G53 and U55 and both carbons 5 and 6 are completely buried. A 17-mer consisting of nucleotides 49-65 (GCGAGUUCGAUCCUCGC) has been found to be a substrate for RUMT. In collaboration with the Santi group at UCSF, we are studying the conformation of this 17mer RNA fragment (and possibly its methylated analog) by solution NMR spectroscopy to determine the conformational changes which occur during this enzymatic reaction. We have used software provided by the Computer Graphics Laboratory MIDAS to display crystal structures of tRNA and its subunits and to monitor NOE violations (NOEshow) during our structure calculations (AMBER 4.1).